Prospects for a speedy settlement in the tit-for-tat transatlantic clash over aircraft subsidies appeared dim on Wednesday as a case involving Boeing resumed at the World Trade Organization (WTO).

The European Union and the United States are pursuing competing complaints with the WTO over tens of billions of euros and dollars in state support provided to Boeing and Airbus, rivals who both posted record results in 2007.

While both sides could be found in violation of international trade rules if the WTO cases unfold to the verdict stage, industry and government sources said no meaningful negotiations were underway to resolve the issues.

As the WTO panel gathered to hear a second set of arguments in the European complaint against Boeing, Rainer Ohler, Airbus's senior vice-president for public affairs and communications, accused officials of the US group of having imposed "unrealistic" preconditions on talks.

"We have suggested from the beginning that a balanced, negotiated settlement would be the best solution for all sides as, in a case of this complexity and scope, any delay in inevitable discussions benefits only the lawyers," Ohler said.

Boeing, in turn, said its European Commission (EC) counterparts had offered no momentum towards negotiation.

"Thus far we have seen no evidence of an EC interest to resolve this dispute," Boeing lawyer Robert Novick said.

The US and European aircraft makers compete in a market worth about USD$80 billion a year. Both recorded strong orders and deliveries in 2007, though they may suffer in 2008 if the global economy falters.

It remains unclear when the twin WTO dispute panels will release their initial rulings.

The panel in the case against Airbus, in which the United States alleges the company got grants and loans at unfairly favorable rates in the form of "launch aid", is expected to release a descriptive section of its report to parties in May.

The two sides would then have a week to comment on the evidence included, before the panelists draw up their analysis and conclusions in an interim report, which could take weeks or months, officials said.

In the case against Boeing, which hinges on the provision of research and development assistance from NASA and the US Department of Defense, the WTO panel is expected to meet again for at least one round of questions before proceeding to the report-writing stage later this year.

A ruling issued in the Airbus case before the Boeing conclusions are finished could put the European Union at a disadvantage in any negotiations that do occur.

An EU official, who spoke on condition of anonymity, said it was possible the two reports would be issued together.

"It may make sense to deal with these issues more or less at the same time," the EU official said.